"With the [National Fenestration Rating Council] mandate to require [insulating glass] testing, manufacturers have to have a compliant product. If you don't, you'll be shut out from the marketplace. This is serious stuff," says Dan Braun, vice president of regional operations for Architectural Testing Inc., York, Pa. The following are tips to successful insulating glass testing.

The most common failures to the certification testing, specified in ASTM E2190, occur in four general areas, Braun said: handling and thermal breakage, chemical/volatile fog, gas fill, and seal durability.

For handling, "each piece of glass sent to testing is handled about 15 times, significantly more than the average production unit," he said. To minimize the risk of breakage during handling, Braun recommends that manufacturers:

Use shipping containers that properly cushion the glass and provide separation for each unit.

Polish or sand edges to reduce the risk of chipping and thermal breakage, and create units that are safer to handle.

Inspect glass edge before shipping.

Problems with chemical/volatile fog, the result of off gassing of paints and oils, are more common in residential applications, because of the more widespread use of grills, blinds and other decorative components, Braun said. Common causes of fog failures include: glass cleanliness, volatiles in paints, cutting oils, fingerprints, volatiles in plastics and sensitivity of low-emissivity coatings. If a unit fails the volatile fog test, it will fail the entire E2190 test, so manufacturers should make sure their units are able to pass. He recommends manufacturers:

Acquire a chemical fog chamber to test units on their own.

Complete the fog test before the weather cycling test—if the fog test fails, the manufacturer will not have spent time and money on the weather cycling portion unnecessarily.

The gas content component of the test measures the ability of a unit to retain its gas fill. Braun recommends manufacturers:

Take grids and spacers into account.

Acquire a GasGlass device to test fill on units in the plant.

The final portion of the text looks at seal durability of units after intense weather cycling. Poor glass cleanliness, low-E coating corrosion, sealant voids, incomplete sealant mixing, and poor primary and secondary sealant adhesion can all lead to seal failure, Braun said. To avoid failures, he recommends manufacturers:

Consider edge-deleting to avoid low-E corrosion.

Educate and train staff on fabricating small test-sized samples to ensure that the production quality is equal to the quality with normal-sized units.

Complete post-fabrication inspection of units.

Looking forward, manufacturers will see certification considerations for vacuum glazed units, certification of gas mixes, and increased attention in certification testing from the Department of Energy, Braun said.